T/myeloid mixed-phenotype acute leukemia treated with venetoclax and decitabine:A case report

BACKGROUND Mixed-phenotype acute leukemia(MPAL)is characterized by acute undifferentiated leukemia with blasts co-expressing myeloid and lymphoid antigens.However,consensus regarding the ideal management strategy for MPAL is yet to be established,owing to its rarity.CASE SUMMARY A 55-year-old male was diagnosed with T/myeloid MPAL.Vincristine,prednisolone,daunorubicin,and L-asparaginase were administered as induction chemotherapy.Septic shock occurred 10 days after induction,and bone marrow examination following recovery from sepsis revealed refractory disease.Venetoclax and decitabine were administered as chemotherapy-free induction therapy to reduce the infection risk.There were no serious infections,including febrile neutropenia,at the end of the treatment.After receiving two additional cycles of venetoclax/decitabine,the patient underwent haploidentical peripheral blood stem-cell transplantation and achieved complete response(CR)to treatment.CONCLUSION CR was maintained in a patient with MPAL who underwent haploidentical peripheral blood stem-cell transplantation after additional venetoclax/decitabine cycles.

Laboratory Diagnosis of Acute Leukemia in Kenya: The Gaps and Opportunities

Acute leukemia (AL) is a malignant disease of the bone marrow in which hematopoietic precursors are arrested in an early stage of development. The diagnosis of leukemia and lymphomas, beyond morphology, is limited in low-resource countries including Kenya. Morphological diagnosis includes Cytological and Histological assessment of blood, bone marrow aspirates and tissues on suspected Acute leukemia patients. The World Health Organization (WHO, 2016) international guidelines on Acute leukemia diagnosis recommend that cytogenetic analysis, appropriate molecular genetics, Fluorescent in situ Hybridization (FISH) testing, and flow cytometric immuno-phenotyping should be done in addition to a morphologic assessment of Acute Leukemia. In facilities where resources are relatively available, immunophenotypic and genetic features have resulted not only in providing a more accurate leukemia diagnosis but also in identifying antigens or genes that can then be targeted for therapy. This article will look at the gaps in the diagnosis of Acute leukemia in low-resource settings like Kenya and opportunities available to improve diagnosis.

Study on the Clinical Efficacy of Megestrol Acetate Dispersible Tablets in Adjuvant Treatment of Acute Leukemia

Objective:To analyze the clinical efficacy of megestrol acetate dispersible tablets in the adjuvant treatment of acute leukemia.Methods:80 patients with acute leukemia admitted from December 2021 to December 2022 were randomly divided into two groups.The control group underwent chemotherapy,and the observation group took megestrol acetate dispersible tablets and underwent chemotherapy.The effect of the treatments were evaluated by analyzing the albumin(Alb)and prealbumin(Palb)indicators,and the adverse reactions were observed.Results:There was no significant difference in Alb and Palb indexes between the two groups before treatment(P>0.05).After treatment,Alb and Palb indexes in the observation group were greater than those in the control group(P<0.05).The incidence of adverse reactions in the control group was 20.00%,which was significantly higher than the observation group(5.00%),with P<0.05.Conclusion:The combination of megestrol acetate dispersible tablets and chemotherapy is more effective in treating patients with acute leukemia,and the Alb and Palb indexes can be optimized.Besides,there are fewer adverse reactions,which means that the treatment is relatively safe.

Adoptive immunotherapy for acute leukemia:New insights in chimeric antigen receptors

Relapses remain a major concern in acute leukemia. It is well known that leukemia stem cells(LSCs) hide in hematopoietic niches and escape to the immune system surveillance through the outgrowth of poorly immunogenic tumor-cell variants and the suppression of the active immune response. Despitethe introduction of new reagents and new therapeutic approaches, no treatment strategies have been able to definitively eradicate LSCs. However, recent adoptive immunotherapy in cancer is expected to revolutionize our way to fight against this disease, by redirecting the immune system in order to eliminate relapse issues. Initially described at the onset of the 90's, chimeric antigen receptors(CARs) are recombinant receptors transferred in various T cell subsets, providing specific antigens binding in a non-major histocompatibility complex restricted manner, and effective on a large variety of human leukocyte antigen-divers cell populations. Once transferred, engineered T cells act like an expanding "living drug" specifically targeting the tumor-associated antigen, and ensure long-term antitumor memory. Over the last decades, substantial improvements have been made in CARs design. CAR T cells have finally reached the clinical practice and first clinical trials have shown promising results. In acute lymphoblastic leukemia, high rate of complete and prolonged clinical responses have been observed after anti-CD19 CAR T cell therapy, with specific but manageable adverse events. In this review, our goal was to describe CAR structures and functions, and to summarize recent data regarding pre-clinical studies and clinical trials in acute leukemia.

PROGNOSTIC SIGNIFICANCE OF EXPRESSION OF SURVIVIN IN ACUTE LEUKEMIA

Objective: To investigate the expression of survivin gene and its significance in acute leukemia. Methods: The expression of surviving in 134 acute leukemia patients and 4 leukemia cell lines was detected by RT-PCR and immunofluorescence analysis. Results: We detected survivin expression in 78 of 134 acute leukemia patients and all the cell lines but not in normal controls and anemia patients. Survivin gene expression correlated with a lower white blood cell count, which was 11×109/L and 48×109/L in the positive and negative group respectively (P<0.01 by the Mann-Whitney test). In 55 cases of FAB M1/M2/M3, it was associated with leukemic cell maturation(P<0.01 by the Fisher test). Survivin expression was strongly related to survival time of acute leukemia patients (P<0.05). Conclusion: These data suggest that survivin expression may be considered as a new unfavorable prognostic factor for acute leukemia due to its important role in apoptosis inhibition that influences disease outcome.

Application of CD45/SSC Gating Multiparameter Flow Cytometry in the Classification of Acute Leukemia——An Analysis of 139 Cases

In order to study the significance of flow cytometry immunophenotyping in the diagnosis of acute leukemia, CD45/SSC gating multiparameter flow cytometry (FCM) was utilized to analyze the immunophenotypes of 139 cases of acute leukemia. 139 cases of acute leukemia were enrolled in our hospital from April 1998 to April 2000. Morphological analysis and FCM immunophenotypic tests were conducted on all cases. Our results showed that CD45/SSC gating multiparameter flow cytometry immunophenotyping could reflect the origin of leukemic cells specifically. It is one of the important methods for the diagnosis of ALL, AML, and HAL. CD45/SSC gating multiparameter FCM analysis is a good technique for immunophenotyping. FCM immunophenotypic analysis can help improve the diagnosis and classification of acute leukemia, and extend the use of FCM in clinical practice.

Detection of Cytokine Expression Patterns in the Peripheral Blood of Patients with Acute Leukemia by Antibody Microarray Analysis

The cytokines of acute leukemia （AL） patients have certain expression patterns, forming a complex network involved in diagnosis, progression, and prognosis. We collected the serum of different AL patients before and after complete remission （CR） for detection of cytokines by using an antibody chip. The expression patterns of cytokines were determined by using bioinformatics computational analysis. The results showed that there were significant differences in the cytokine expression patterns between AL patients and normal controls, as well as between acute myeloid leukemia （AML） and acute lymphoblastic leukemia （ALL）. In confirmatory test, ELISA revealed the expression of uPAR in AL. Moreover, the bioinformatic analysis showed that the differentially expressed cytokines among the AL groups were involved in different biological behaviors and were closely related with the development of the disease. It was concluded that the cytokine expression pattern of AL patients is significantly different from that of healthy volunteers. Also, differences of cytokine expression patterns exist between AML and ALL, and between before and after CR in the same subtype of AL, which holds important clinical significance for revealing disease progression.

Role of microRNA dysregulation in childhood acute leukemias:Diagnostics,monitoring and therapeutics:A comprehensive review

MicroRNAs(miRNAs)are short noncoding RNAs that regulate the expression of genes by sequence-specific binding to mRNA to either promote or block its translation;they can also act as tumor suppressors(e.g.,let-7b,miR-29a,miR-99,mir-100,miR-155,and miR-181)and/or oncogenes(e.g.,miR-29a,miR-125b,miR-143-p3,mir-155,miR-181,miR-183,miR-196b,and miR-223)in childhood acute leukemia(AL).Differentially expressed miRNAs are important factors associated with the initiation and progression of AL.As shown in many studies,they can be used as noninvasive diagnostic and prognostic biomarkers,which are useful in monitoring early stages of AL development or during therapy(e.g.,miR-125b,miR-146b,miR-181c,and miR-4786),accurate classification of different cellular or molecular AL subgroups(e.g.,let-7b,miR-98,miR-100,miR-128b,and miR-223),and identification and development of new therapeutic agents(e.g.,mir-10,miR-125b,miR-203,miR-210,miR-335).Specific miRNA patterns have also been described for commonly used AL therapy drugs(e.g.,miR-125b and miR-223 for doxorubicin,miR-335 and miR-1208 for prednisolone,and miR-203 for imatinib),uncovering miRNAs that are associated with treatment response.In the current review,the role of miRNAs in the development,progression,and therapy monitoring of pediatric ALs will be presented and discussed.

Antitumor Effect of Interferon-α on U937 Human Acute Leukemia Cells in vitro and Its Molecular Mechanism

In order to investigate the antitumor effect and molecular mechanism of interferon-α （IFN-α） on human acute myeloid leukemia cell line U937 cells in vitro, the proliferation of U937 cells was determined by MTT assay, the apoptosis rate was analyzed by flow cytometry （FCM）, and the mRNA expression of cell cycle regulatory protein cyclin E was detected by RT-PCR. The results showed that IFN-α could inhibit the proliferation of U937 cells significantly in a dose- and time-dependent way （P〈0.01）, and induce the apoptosis of U937 cells also in a dose- and time-dependent manner at the concentration of 1000--4000 U/L （P〈0.01）. The apoptosis rate of U937 cells was even over 50% when cultured with IFN-α for 36--48 h at the concentration of 2000 -4000 U/L. Moreover, the expression of cyclin E mRNA was markedly inhibited by the addition of IFN-α, and the inhibition was time-dependent （P〈0.01）. It was concluded that the anti-leukemia mechanism of IFN-α might be correlated with its antiproliferative and apoptotic inducing effects, and the down-regulation of the cyclin E expression might be one of its molecular mechanisms.

Expression of Survivin,CDK4,Ki-67 and Clinical Significance in Pediatric Acute Leukemia

The expression of Survivin, CDK4 and Ki-67 and the clinical significance in pediatric acute leukemia （AL） were investigated. The expression of Survivin, CDK4 and Ki-67 proteins was detected by using immunohistochemical assay in 37 children with AL and l0 children with normal bone marrow as controls. The positive expression rate of Survivin, CDK4 and Ki-67 was 45.9 %, 56.8 %, and 40.5 % respectively in 37 AL children, which was significantly higher than in control group accordingly （P〈0.05）. The expression of Survivin was positively correlated with CDK4 （P=0.007） and Ki-67 （P=0.008）. In conclusion, all Survivin, CDK4 and Ki-67 proteins are over-expressed in pediatric AL and involved in the modulation of apoptosis and proliferation in pediatric AL.

EXPRESSION AND CLINICAL SIGNIFICANCE OF MULTIDRUG RESISTANCE GENE AND MULTIDRUG RESISTANCE-ASSOCIATEDPROTEIN GENE IN ACUTE LEUKEMIA

Objective: To evaluate the expression and clinical significance of multidrug resistance gene (mdr1) and multidrug resistance-associated protein (MRP) gene in acute leukemia. Methods: The expression of mdr1 and MRP assay in 55 patients with acute leukemia (AL) by reverse transcription polymerase chain reaction (RT-PCR). Results: The mdr1 and MRP gene expression levels in the relapsed AL and the blastic plastic phases of CML were significantly higher than those in the newly diagnostic AL and controls. The mdr1 and MRP gene expression levels in the clinical drug-resistant group were significantly higher than those in the non-drug-resistant group. The complete remission (CR) rate in patients with high mdr1 expression (14.3%) was significantly lower than that with low mdr1 expression (57.5%); similarly the CR rate in patients with high MRP level was also lower than that with low MRP level. Using both high expression of mdr1 and MRP gene as the indicator for evaluating multidrug resistance (MDR), the positive predictive value and accuracy increased in comparison with single gene high expression. Conclusion: Elevated level of mdr1 or MRP gene expression might be unfavorable prognostic factors for AL patient and may be used as an important index for predicting drug-resistance and relapse in AL patient. Measuring both mdr1 and MRP gene expression would increase accuracy and sensibility of evaluating MDR in acute leukemia.

Meta-analysis of Cytochrome P4501A1 MspI Gene Polymorphism and Childhood Acute Leukemia

Objective To investigate the relationship between cytochrome P4501A1 （CYPIA1） Msp I gene polymorphism and childhood acute leukemia （AL）. Methods Relevant literature was extensively searched and screened by Pubmed and Wanfang Database, Chinese Science Journal Database and Chinese Journal Net. Various data consolidation, combined OR values and their 95% CI were tested by RevMan 4.2; Funnel plots were used for the bias analysis. Results Six related literatures were found to meet the requirements. According to heterogeneity results, there was no significant difference in homozygous types（P〉0.05）, while there was significant difference in two others types （P all〈0.05）. For wild CYPIAIMspl homozygous for the reference group, Combined OR of heterozygous mutation, homozygous, heterozygous ＋ homozygous mutation in AL and control groups were 1.18, 0.96, and 1.10 respectively. Subgroup analysis： Z values of CYP1A1Mspl homozygous, heterozygous ＋ homozygous in the acute lymphoblastic leukemia （ALL） and the control group were 0.10 and 0.76 respectively, Z values in non-acute lymphoblastic leukemia and control group were 0.74 and 0.75. Conclusion There is no correlation between CYP1A1Mspl gene polymorphism and the susceptibility of childhood AL.

Reliability and validity of the Chinese version of the PedsQL Multidimensional Fatigue Scale in children with acute leukemia

Background:The PedsQL Multidimensional Fatigue Scale(PedsQL^(TM)MFS)is widely used to rate fatigue in children living in English-speaking countries.However,insufficient instruments are available to conduct parallel assessment on fatigue in parents and children in China.In this regard,an appropriate measurement method must be developed.Objectives:This study aims to determine the reliability and validity of the Chinese-language PedsQL^(TM)MFS.Methods:Children with cancer(n=125)and their parents were surveyed in Guangzhou,China.The parents of children aged 2e4 years completed the PedsQL^(TM)MFS proxy reports,whereas the other children and their parents completed the questionnaires by themselves.Results:The PedsQL^(TM)MFS-Chinese version demonstrated satisfactory internal consistency reliability(child self-report Cronbach's a=0.87;parent self-report Cronbach's a=0.93).The factor loadings of the items ranged from 0.78 to 0.87 for general fatigue,0.56e0.78 for sleep/rest fatigue,and 0.62e0.89 for cognitive fatigue.Conclusion:This study proves that the PedsQL^(TM)MFS-Chinese version is an effective tool for screening fatigue in Chinese children with cancer.

TELOMERASE ACTIVITY AND hTERT mRNA EXPRESSION IN ACUTE LEUKEMIA

Objective: To investigate the clinical implications of telomerase activity and human telomerase reverse transcriptase (hTERT) expression as useful diagnostic marker in acute leukemia. Methods: Expression of hTERT was detected by reverse transcription-polymerase chain reaction (RT-PCR) in 24 cases with acute leukemia and in 12 normal persons. Quantitative levels of telomerase activity were examined by polymerase chain reaction enzyme-linked immunoassay (PCR-ELISA). Results: In the bone marrow and peripheral blood of 24 acute leukemia, telomerase activity was detected in 75% of the samples, with absorbances (A) of 0.538±0.062 and 0.463±0.054, respectively. Whereas in 12 normal peripheral blood, telomerase activity had only a positive rate of 8.3%, with A value of 0.16±0.012. telomerase activities in the bone marrow and peripheral blood of acute leukemia were significantly higher than in normal control (P<0.05). RT-PCR analysis revealed that hTERT mRNA was expressed in 79.17%(19/24) of acute leukemia, but in only 1 of 12 normal peripheral blood. In 24 acute leukemias, 17 cases had both positive telomerse activity and hTERT mRNA expression. The expression of hTERT mRNA is correlated with telomerase activity (P<0.01). Conclusion: Telomerase and hTERT mRNA could be useful in diagnosis of acute leukemia. hTERT gene expression was strongly associated with telomerase activity in acute leukemia. Key words Telomerase - hTERT - Acute leukemia CLC number R733.71 Foundation item: This work was supported by the Guangdong Provincial Key Foundation of Science and Technology Program(No. 021195).Biography: HE Dong-mei(1968–), female, doctor of medicine, associate professor, Jinan University Medical College, majors in gene diagnosis and therapy of leukemia.

Hematopoiesis reconstitution and anti-tumor effectiveness of Pai-Neng-Da capsule in acute leukemia patients with haploidentical hematopoietic stem cell transplantation

BACKGROUND With the rapid development of haploidentical hematopoietic stem cell transplantation(haplo-HSCT),primary poor graft function(PGF)has become a lifethreatening complication.Effective therapies for PGF are inconclusive.New Chinese patent medicine Pai-Neng-Da(PND)Capsule exerts dual effect in promoting hematopoiesis recovery and regulating immunity.Still,the application of PND capsule in hematopoietic stem cell transplantation,especially in the haplo-HSCT setting,has not yet been reported.AIM To evaluate the role of PND capsule in acute leukemia patients with haplo-HSCT.METHODS We retrospectively collected data of acute leukemia patients who underwent haplo-HSCT at the Affiliated People’s Hospital of Ningbo University between April 1,2015 and June 30,2020.Twenty-nine consecutive patients received oral PND capsule from the sixth day to the first month after haplo-HSCT were included in the PND group.In addition,31 patients who did not receive PND capsule during haplo-HSCT were included in the non-PND group.Subsequently,we compared the therapeutic efficacy according to the western medical evaluation indexes and Chinese medical symptom scores,and the survival between the PND group and the non-PND group,using the chi-square test,Fisher’s exact test,and the Kaplan-Meier method.RESULTS The duration of platelet engraftment was shorter in the PND group than in the non-PND group(P=0.039).The PND group received a lower frequency of red blood cells and platelet transfusions than the non-PND group(P=0.033 and P=0.035,respectively).In addition,PND capsule marginally reduced the rate of PGF(P=0.027)and relapse(P=0.043).After 33(range,4-106)months of follow-up,the 3-year relapse-free survival(P=0.046)and progression-free survival(P=0.049)were improved in the PND group than in the non-PND group.Also,the therapeutic efficacy of the PND group according to Chinese medical symptom scores was significantly better than that of the non-PND group(P=0.022).Moreover,the adverse events caused by PND capsule were mild.Nevertheless,there were no significant differences in the duration of neutrophil engraftment,the risk of infection within 100 days after haplo-HSCT,the acute graft-versus-host disease,or the 3-year overall survival between the two groups.CONCLUSION PND capsule could promote hematopoiesis reconstitution,improve the therapeutic efficacy of Chinese medical symptom scores,present anti-tumor effectiveness,and prolong the survival of acute leukemia patients with haplo-HSCT.

Genistein-induced Anticancer Effects on Acute Leukemia Cells Involve the Regulation of Wnt Signaling Pathway Through H4K20mel Rather Than DNA Demethylation

Objective:To investigate the effects and mechanisms of genistein on the gene expression in the Wnt pathway in acute leukemia(AL)cells.Methods:The expression of Wnt pathway genes and cell cycle-related genes were analyzed in two AL cell lines.Pyrophosphate sequencing was performed to determine the methylation degree.Then,the enrichment of H4K20mel and H3K9ac was determined using ChIP-qPCR.Flow cytometry was used to analyze the cell cycle.Results:The IC_(50) of genistein in the two AL cell lines was lower than that for the bone marrow mesenchymal stem cell line.Genistein upregulated H4K20mel,KMT5A and Wnt suppressor genes,including Wnt5a,and downregulated the downstream target genes of Wnt,such as c-myc and β-catenin.The methylation degree and H3K9ac enrichment in the Wnt5a promoter region remained unchanged.However,the enrichment of H4K20mel in the Wnt5a promoter and coding regions increased.In addition,genistein upregulated Phospho-cdc2,Mytl,Cyclin A,Cyclin E2,p21 and Phospho-histone H3,but downregulated Phospho-weel.Cell cycle arrest was induced in the G2/M phase.Conclusion:Genistein inhibits the activation of the Wnt pathway by promoting the expression of Wnt5a through the activation of KMT5A and enrichment of H4K20mel in the Wnt5a gene promoter and coding regions,rather than demethylation.Genistein also blocks the cell cycle in the G2/M phase.Therefore,genistein is a potential anti-leukemia drug.

Correlation between Cyclin A Gene Expression in Adult Patients with Acute Leukemia and Drug Resistance

In order to investigate the relationship between the expression of cyclin A and drug resistance in adult patients with acute leukemia (AL), the mRNA expression of cyclin A, mdr1, TopⅡ α , bcl-2 was detected in 64 adult patients with AL and 20 normal controls by semi-reverse transcription polymerse chain reaction (semi-RT-PCR). It was found that the cyclin A and TopⅡ α mRNA expression levels in drug resistant group were significantly lower than in sensitive group ( P <0.01). Under the same experimental condition no cyclin A mRNA expression was detectable in all normal controls. The mdr1 and bcl-2 mRNA expression levels in resistant group were significantly higher than in sensitive group ( P <0.01). cyclin A and TopⅡ α gene expression levels were closely correlated ( r s =+0.794, P=0.000, n =64) in all AL patients, but cyclin A was not correlated with mdr1 and bcl-2 gene expression levels. In drug resistant group there was a negative correlation between the gene expression levels of cyclin A and mdr1 ( r s =-0.337, P=0.029 ). The 10 AL patients with positive lower expression of both cyclin A and TopⅡ α were all resistant to drugs. Logistic regression of Binary analysis showed the correlation between the lower expression of cyclin A and drug resistance. It was concluded that lower expression of cyclin A gene might be an unfavorable prognostic factor for patients with AL, and detection of both cyclin A and TopⅡ α gene expression would predict drug resistance in AL patients.

Detection of lymphocyte subsets and regulatory T cells in peripheral blood of patients with acute leukemia and its clinical significance

Objective To study the changes of lymphocyte subsets and regulatory T cells in peripheral blood of patients with acute leukemia(AL) and its clinical significance.Methods The different levels of peripheral blood lymphocyte subsets and regulatory T cells of 60 AL patients and 40 normal controls were detected with flow cytometry.Results Compared with the normal controls,the percentages of CD3+ T cells,CD4+ T cells,CD16+CD56+ NK cells and the ratio of CD4+ /CD8+ obviously decreased in newly diagnosed AL group(P <0.05),while their percentages of CD8+ T cells and CD19+ B cells significantly increased(P <0.01).The percentage of CD4+ T cells and the ratio of CD4+ /CD8+ in acute lymphoblastic leukemia(ALL) group were much lower than those in acute myelogenous leukemia(AML) group(P <0.01).Compared with these in control group,the proportions of CD4+ CD25high Treg cells and CD4+ CD25+ T cells in newly diagnosed AL group were significantly increased(P <0.01).Conclusion Cellular immune function is significantly abnormal in patients with AL.Compared with AML patients,ALL patients had poorer cellular immune function.The increased CD4 + CD25high Treg cells might be one of the important reasons of immunosuppression in AL.Detection of lymphocyte subsets and regulatory T cells is of clinical value on the evaluation of therapeutic effect and prognosis in AL patients.

CENTRAL NERVOUS SYSTEM RADIOTHERAPY IN ACUTE LEUKEMIA

From Dec. 1976 through June 1986, 474 patients with acute leukemia were treated with central nervous system (CNS) irradiation for the purpose of preventing relapse of CNS leukemia. Of the whole series, whole cranial irradiation at a dosage of 24 Gy and 4-5 intrathecal instillations of methotrexate (MTX) were given in 149 patients, simple intrathecal instillation of MTX in 44 patients and high dose intravenous MTX in 5 patients; the CNS relapse rates were 4.0%, 20.5% and 40.0% respectively. It was proved by our experience that whole cranial irradiation plus intrathecal MTX is the best approach to prevention of CNS leukemia relapses.

Study on P16 Gene in Acute Leukemia

To stddy the chang of suppressing cancer gene P16 in acute leukemia, the P16 antigen expression of leukemia cell surfaces in 61 cases were investigated with ABC assay and gene structural defects in 51 cases of acute leukemia were examined with multiple comparative PCR method. It was found that antigen expression of P16 in leukemia was obviously lower than that innormal subjects ( P <0 001). At the same time, antigen expression in All was lower than that AML ( P <0 05). No significant difference was found betwee the complete reission (CR) and non remission (NR) subjects from AML and ALL groups ( P >0 05). THe exon 2 of P16 gene showed homozygous deletion only inn4 cases out of 30 cases in ALL. No stuctural defect was revealed in 21 cases of AML. It was suggested that expression defect of P16 gene was a main cause in development and progression of acute leukemia, and structural defect of exon 2 was not a primary molecular event.